Machine Learning · head to head
Comet ML vs Neptune.ai
Comet ML
Machine Learning
Platform for tracking, comparing, and optimizing ML experiments
- From
- Free
- Rated
- -
The short version
- Each has a real cost: Comet ML the free cloud tier caps data at 25,000 spans a month with 60 day retention; Neptune.ai free tier limited to 100 hours per month, exhausted quickly with serious ML work
- They diverge on capability: Comet ML covers Code versioning, Neptune.ai covers Metadata logging.
- Prices and features above were last checked on 30 August 2026.
Where they differ
Only the attributes on which Comet ML and Neptune.ai actually diverge.
| Attribute | Comet ML | Neptune.ai |
|---|---|---|
| Pricing model | freemium | Unknown |
| Platforms | Web, Linux, Mac, Windows | Web, Self-hosted |
Identical on both: starting price (Free), free tier (Yes), user rating (Not yet rated), category (Machine Learning), founded (2017).
What each one covers
Drawn from each product's published feature list. An absence here means we hold no record of it - not that the product lacks it.
Only in Comet ML
- Code versioning
- Hyperparameter optimization
- Production monitoring
- Hugging Face
Only in Neptune.ai
- Metadata logging
- Comparison views
- Custom dashboards
- XGBoost
Both cover
- Experiment tracking
- Model registry
- PyTorch
- TensorFlow
- Keras
- scikit-learn
- Web support
- Linux support
- Mac support
- Windows support
What people use each for
The jobs each tool is most often brought in to do.
Comet ML
- LLM observability and monitoringnot Neptune.ai
- AI agent testing and debuggingnot Neptune.ai
- Experiment tracking for machine learningnot Neptune.ai
- Model registry and version managementnot Neptune.ai
- ML model training monitoringnot Neptune.ai
Neptune.ai
- Machine learningnot Comet ML
- Data analysisnot Comet ML
- Model trainingnot Comet ML
- Predictive analyticsnot Comet ML
Where each one falls short
Documented limitations, not opinions. Every one is a constraint you would hit in normal use.
Comet ML
- The free cloud tier caps data at 25,000 spans a month with 60 day retention
- Retention stays at 60 days even on the paid Pro plan, and extending it is a $29 per 100k spans add on
- Overage on Pro is $5 per additional 100,000 spans
- The free MLOps tier is a single user with 100 GB of storage and training hours governed by a fair usage policy
- Pro MLOps is $19 per user per month and caps the team at 10 users
Neptune.ai
- Free tier limited to 100 hours per month, exhausted quickly with serious ML work
- Lacks hyperparameter sweeps compared to Weights and Biases
- No pipeline orchestration or broader MLOps lifecycle management
- Dashboard visualization limitations - automatic resizing affects visualization order and size
- Cloud-based SaaS only (as of last available service) requires internet connectivity
Pricing, plan by plan
Comet ML
Free- Free CloudFree
- Up to 10 team members
- 25,000 spans per month
- 60-day data retention
- Pro Cloud$19/month
- Up to 50 team members
- 100,000 spans per month
- 60-day data retention
- MLOps FreeFree
- 1 user with fair usage policy
- Experiment tracking
- Dataset management
- MLOps Pro$19/user/month
- Up to 10 users
- 1,500 training hours included
- 500GB storage included
Neptune.ai
FreeNo published plan breakdown. See the Neptune.ai review.
Which should you pick?
Choose Comet ML if
- You need code versioning.
- You want to start without paying.
- You work on Web, Linux, Mac, Windows.
- You also want hyperparameter optimization.
Choose Neptune.ai if
- You need metadata logging.
- You want to start without paying.
- You work on Web, Self-hosted.
- You also want comparison views.
Questions people ask
- Is Comet ML or Neptune.ai better?
- Neither clearly leads. Comet ML starts at Free and Neptune.ai at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
- Which is cheaper, Comet ML or Neptune.ai?
- Comet ML starts at Free and Neptune.ai at Free.
- Does Comet ML or Neptune.ai run on more platforms?
- Comet ML runs on Web, Linux, Mac, Windows. Neptune.ai runs on Web, Self-hosted.
- Can I use Comet ML for free?
- Both have a free tier, so you can try either at no cost before committing.
- What is Comet ML best used for?
- Comet ML is most often used for llm observability and monitoring, ai agent testing and debugging, experiment tracking for machine learning, model registry and version management. Of those, llm observability and monitoring and ai agent testing and debugging are not what Neptune.ai is typically brought in for.
- What can Comet ML do that Neptune.ai cannot?
- Comet ML covers Code versioning, Hyperparameter optimization, Production monitoring, Hugging Face. Neptune.ai covers Metadata logging, Comparison views, Custom dashboards, XGBoost. Both handle Experiment tracking, Model registry, PyTorch, TensorFlow.
Answered from the vendors’ own pages
Comet ML: Does Comet.ml offer a free plan?
Yes, Comet.ml offers free tiers for both Opik (cloud observability) and MLOps platforms. Free Cloud Opik includes up to 10 team members and 25,000 spans/month. Free MLOps tier is limited to 1 user.
SourceNeptune.ai: Does Neptune.ai support self-hosting?
Yes. Neptune can be self-hosted on a Kubernetes cluster with ClickHouse, MySQL, and Redis dependencies, allowing organizations to maintain full data control.
SourceComet ML: How many team members can use the free Comet.ml tier?
Free Cloud supports up to 10 team members. The Pro Cloud plan supports up to 50 team members at $19/month.
SourceNeptune.ai: What machine learning frameworks does Neptune integrate with?
Neptune integrates with PyTorch, TensorFlow, Keras, scikit-learn, XGBoost, LightGBM, Hugging Face Transformers, and Optuna for hyperparameter optimization.
SourceComet ML: What is a span in Comet.ml pricing?
A span represents a single tracked operation such as model requests or function calls. Free Cloud tier includes 25,000 spans per month.
SourceNeptune.ai: What is the cost for a team of 10 data scientists?
Neptune's Team plan costs $49 per user per month, resulting in $490/month for 10 users, comparable to Weights and Biases at $50/user.
SourceComet ML: Does Comet.ml offer academic pricing?
Yes, a free Pro plan is available for academic users; verification is required via signup.
SourceNeptune.ai: When is Neptune.ai shutting down?
Neptune.ai is shutting down its external SaaS service on March 5, 2026, following its acquisition by OpenAI in December 2025. Customers must export and migrate data before that date.
SourceRelated pages
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